An emulsion is a mixture of two or more immiscible liquids, one being present in the other in the form of droplets. In the classic emulsion, the oil may either be dispersed in the water (oil-in-water or o/w emulsion) or the water dispersed in the oil (water-in-oil, w/o, or inverse emulsion). This terminology is important because of the external phase, a key factor in emulsion formulation and design.
In emulsion formulation, the goal is to achieve the best combination of emulsion properties to fulfill the application needs and stability requirements. The key or active ingredients may or may not be the major ingredient. The main ingredient is most frequently the continuous phase and this dictates the type of emulsion, o/w or w/o. For economic as well as technical reasons, most commercial emulsions are oil-in-water and have low oil (internal) phase levels.
The use of the least amount of emulsifier is possible when a choice is made that most nearly matches the requirements for ionic type, HLB (hydrophile-lipophile balance), and the emulsifier chemical type.
The choice of ionic type: anionic, cationic, amphoteric or nonionic, will influence many properties of the final emulsion. The HLB is an expression of the relative simultaneous attraction of an emulsifier for water and oil (or for the two phases of the emulsion system being considered). It is determined by the chemical composition and the extent of ionization of the emulsifier. For example, ionic emulsifiers change HLB values radically with change in pH and/or salt content of the formula whereas nonionic emulsifiers exhibit a more constant HLB under these circumstances.
Emulsions are used in a variety of fields such as textiles, leather and metal treatment; foods, cosmetics, pharmaceuticals and paints; in agricultural chemicals, polymerizations, cleaning and polishing; and ore and petroleum recovery. In the personal care field which includes products such as cleansing bars and shampoos, cold creams, after-shaves, anti-perspirants, lotions and moisturizers, and pharmaceutical ointments, just to name a few, emulsifiers are added to both emulsify and thicken these compositions.
Emollients is the name given to a class of chemicals which are used in topical personal care preparations such as facial cleaners, handcreams and the like, to exert a softening and protective effect upon skin tissue. Mineral oil is widely used in personal care products as an emollient because of its low cost. However, mineral oil has an undesirable oily feel which is carried over into the finished product. There thus exists a need for compounds which will reduce the oily feel of mineral oil without reducing its emolliency. Moreover, typical personal care preparation utilize both an emulsifier for thickening and emulsifying the preparation and an emollient for providing good skin-feel if the product is intended to come into contact with skin. The use of two separate components to achieve the desired result is, as expected, more expensive and adds to the production costs of the products. Thus, a primary object of the present invention is to provide a compound which has both emulsifying and/or emolliency imparting properties.